Ch'odo-class Patrol Boat, 51, 'Chae Jeong-bo' – Hero of the Republic

ChieftainWarrior · September 4, 2024, 8:24am

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Ch’odo-class, 51, ‘Chae Jeong-bo’

TL;DR: An indigenous class of patrol boats derived from the Soviet Pr. 201M submarine chaser, armed with a forward 76mm, two 37mm cannons, and either two 12.7mm cannons or three dual 14.5mm cannons

History
After Japan’s surrender in 1945, Korea was immediately split down the 38th parallel into two occupied zones – the Soviet Union in the North, and the USA in the South. While there were attempts at unified governance, such as the establishment of the People’s Republic of Korea – a network of people’s committees across the peninsula –, they were short-lasting, and the two superpowers continued to disagree on the future of the country. In 1950, full-scale war broke out.

The newly founded Democratic People’s Republic of Korea (DPRK) had virtually no navy during the war, relying on basic Soviet torpedo boats, as well as a variety of civilian boats converted to military use as impromptu gunboats.

Following the signing of the Korean Armistice in 1953, the DPRK sought to re-equip its navy (the Korean People’s Navy, KPN or KPANF) and replace its dated inventory. This involved – to begin with – importing Soviet and Chinese ships, before transitioning to domestically-produced ships beginning around the 1960s and essentially halting imports, following the principles of Juche (self-reliance).

According to North Korean sources, however, their very first domestically-produced ship was built at Wŏnsan Shipyard in 1949, just before the outbreak of war. This ship is Patrol Boat 41, ‘Worker’ (로동자) and is of an all-steel construction. It has only been seen a few times, and appears to have been scrapped or taken out of service, last being definitively sighted and dated to a film in 1982. While claimed to be built in 1949, a much more likely explanation is that it was constructed in the late 1950s following imports of the Soviet Pr. 201M submarine chaser, with some key differences, such as a narrower beam, a funnel amidships, and upgraded weaponry.

Scale model of Patrol Boat 41

Strangely, however, North Korea also claim another ship as the ‘first built after liberation’ – Patrol Boat 51. This is almost certainly false. Patrol Boat 51 is widely (and likely correctly) claimed to be part of the Ch’odo-class, a class we know was constructed from the late 1950s to the early 1960s, and bears many signs that it is a more refined design from Patrol Boat 41. These include the absence of the funnel, something rarely seen on any other KPANF ships, as well as better radars, although very similar weaponry.

North Korea is known to have received a number of Pr. 201Ms but this variant was first constructed in 1958, and at least four Pr. 201s were spotted in North Korea in 1957, according to the CIA, alongside one Ch’odo-class ship. This is backed up by a number of other sources that say either six or eight Pr. 201s were imported from 1957-1961, with the rest being constructed under license from 1968 onwards, most likely to Pr. 201M standard.

I found one reference online to supposed US intelligence reporting two North Korean patrol boats with the numbers 51 and 52 in July of 1950, but I can’t find the source of this information, nor does it necessarily mean these were ships of the Ch’odo-class.

Four ships are believed to be part of the Ch’odo-class, each differing slightly in weaponry, hence some disparities between other ships and Patrol Boat 51. One Ch’odo-class is believed to have been retired some time in the 1980s, leaving only three. Patrol Boat 51 was probably the first one constructed – this means it was constructed by 1957, if the CIA report didn’t treat Patrol Boat 41 as part of the Ch’odo-class. It has been seen a few times, likely still being in service to this day.

Screenshot 2024-08-13 at 13.08.01

Satellite image of two ships at Munch’ŏn naval base (39.304617, 127.395663) in 2024. I believe the ship to the left is one of the modified Pr. 201s, whereas the other is Patrol Boat 51.

Patrol Boat 51 is named ‘Chae Jeong-bo’ after a naval commander in the KPANF, who was killed in battle in October 1950, and was posthumously awarded the ‘Hero of the Republic’ title. Supposedly, he sank 12 ships by laying mines after he ran ‘hundreds of miles through the night’ to speak to his division leader to tell him to ‘unconditionally carry out the orders of the great leader’ [lay more mines]. It appears as if the ship was initially numbered 51, and then given the name at a later date.

(Left) Chae Jeong-bo shown on North Korean TV, strangely in front of the Patrol Boat 41 model; (Right) Chae Jeong-bo’s grave

Characteristics
The forward armament of the Ch’odo-class, and by extension Patrol Boat 51, is subject to a lot of confusion. While more modern sources (Stijn and Oliemans, 2020) label it as an 85mm cannon, similar to ships like the Sariwŏn-class, Ch’ŏngjin-class or Taech’ŏng-I-class, early reports by the CIA label it a (probable) 76.2mm cannon, and inspection of the few images of Patrol Boat 51 support this claim. The cannon appears very similar to that of the earlier Patrol Boat 41 – the Soviet 76mm 3-K. The only differences appears to be that the cannon is mounted slightly further back on Patrol Boat 51, and the gunshield has slightly angled sides.

Forward cannon of Patrol Boat 51 (left) and Patrol Boat 41 (centre and right)

While North Korea did receive 85mm AA guns from both the Soviet Union (52-K) and China (Type 72 – Chinese modernised 52-K), these cannons have a distinctive muzzle brake which distinguishes them from the 3-K, which the cannon on Patrol Boat 51 lacks. Otherwise, these weapons are almost identical, and impossible to tell apart from the grainy images available. In my opinion, it makes more sense for North Korea to have mounted the 76mm cannon.

The 76mm 3-K can fire APHEBC, HE and HE-TF rounds – its APHEBC rounds have 119mm of penetration at 100m. The gun can fire relatively quickly, with a maximum rate of fire of 5s on the land-based YaG-10 (29-K) in-game.

The aft of the ship has two mounts for 37mm 61-K cannons. These guns have a fire rate of 160 rpm, and can fire HE, AP and HVAP rounds. The AP and HVAP rounds penetrate 68mm and 82mm at 100m respectively. The ship – in its original specification – had two 12.7mm DShKs on the platform just behind the bridge, one on either side. In a later configuration, these were replaced with two dual 14.5mm cannons.

Hard to discern, but this scale model shows only single 12.7mm machine guns

Dual 14.5mm cannons, pointed directly upwards

It also appears that Patrol Boat 51 has – at least for some of its lifespan – another dual 14.5mm cannon behind the aft 37mm cannons. CIA reports appear to have misidentified this as another 37mm cannon. This appears to have been added when the 12.7mm DShKs were changed to dual 14.5mm KPVs.

An unknown Ch’odo-class, with the rear dual 14.5mm clearly visible

Unlike with Patrol Boat 41, the dimensions and other details about the ship have not been revealed by North Korea. We can make some good estimations, however. If the ship in the satellite images is Patrol Boat 51, it has a length of ~43.5m and a beam of ~5.1m. This is very close to the dimensions of Patrol Boat 41, which has a length of 42.3m and a beam of 5.3m, and the Pr. 201M, with a length of 41.9m and a beam of 6.1m. The Pr. 201M has a full displacement of 213t and Patrol Boat 41 has a full displacement of 235t, and as such Patrol Boat 51 is probably also in the 235t region, given the near identical weapons systems and dimensions, although may be slightly less due to the absence of the funnel. It likely has three 40DM diesel engines, providing a total output of 6600 hp, enabling the ship to reach speeds around 27 knots (50 km/h).

Conclusion
Patrol Boat 51 represents one of the DPRK’s earliest domestic ships, and a fairly unique class at that. It would fit at a BR of around 2.7-3.0 in a future North Korean coastal tree, either as a sub-tree for China or as part of a United Korean tree.

Specifications

General
Displacement: ~235t
Engine: 6600bhp
Top Speed: 27 knots (50 km/h)
Crew: >28
Armament:
Main Armament
1x 76mm 3-K ‘M1931/M1938’

AA Armament
2x 37mm 61-K
2x 12.7mm DShK; OR 3x dual 14.5mm KPV
Sensors and Systems:
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